Antarctic Minke whales at heart of 'ocean quack' mystery

The mystery of a bizarre quacking sound heard in the ocean has finally been solved, scientists report.

The noise, nicknamed "the bio-duck", appears in the winter and spring in the Southern Ocean, and has baffled researchers for decades.

Now underwater acoustic recorders have revealed its source is the Antarctic Minke whale.

The findings are published in the Royal Society's journal Biology Letters.